Generate the main Android.mk, so the version number is not hardcoded.

We include the generated file in the distribution, so users won't
have run configure if they are building for Android.

Android.mk.in

@@ -37,7 +37,7 @@ strongswan_CFLAGS := \
 	-DUSE_VSTR \
 	-DROUTING_TABLE=0 \
 	-DROUTING_TABLE_PRIO=220 \
-	-DVERSION=\"4.4.0\" \
+	-DVERSION=\"@PACKAGE_VERSION@\" \
 	-DPLUGINS='"$(strongswan_PLUGINS)"' \
 	-DIPSEC_DIR=\"/system/bin\" \
 	-DIPSEC_PIDDIR=\"/data/misc/vpn\" \

Makefile.am

@@ -6,8 +6,15 @@ endif
 
 ACLOCAL_AMFLAGS = -I m4/config
 
-EXTRA_DIST = Doxyfile.in CREDITS Android.mk
+EXTRA_DIST = Doxyfile.in CREDITS Android.mk.in Android.mk
 CLEANFILES = apidoc Doxyfile
+BUILT_SOURCES = Android.mk
+MAINTAINERCLEANFILES = Android.mk
+
+Android.mk :	Android.mk.in
+		sed \
+		-e "s:\@PACKAGE_VERSION\@:$(PACKAGE_VERSION):" \
+		$(srcdir)/$@.in > $@
 
 Doxyfile :	Doxyfile.in
 		sed \